Compounding alternators.



No. 7l3,022.- Patented Nov. 4, I902.

c. P. srenmnt. COIPOUNDING Aus'nunons.

(Application Med Apr. 16, 1002. (lo Iodel.)

' 3 Sheds-Shut I.

Flel.

Wrrmassrss v Chen "lee C l'nrnetz W by Mi;

INVENTOQ'.

r: NORM! warms co. PNOTO-UTHQ. WAsHmmQN, n c

' No. 7I3,022. Patented Nov. 4, I902.

C. P. STEINMETZ.

CUIPOUNDING ALTERNATORS. A nmm filed rim, 1902. (No Iodel.) -3Shoots-Shoot 2.

2 I Witnesses: c Charles P Stemrnetz THII mus mus co. mvaumou WASNINGYOLofc.

Patented Nov. 4, I902.

c. P. snmuz. COIPOUNDING ALTEQRNATORS.

(ApplicM-ion filed Apr. 18, 1002.)

3 sum-shut 3.

(No Iod d.)

Inventor. Charles P. Steinmetz.

Witnesses T! not-v: vulnco. 'nnrcmmo wan-woven. u. c.

UNITED STATES PATENT OFF-ICE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEvV YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEIV YORK.

COMPOUNDING vALTERNATORS.

SPECIFICATION forming part of Letters Patent N 0. 713,022, datedNovember 4, 1902. Original application filed August 20, 1897. Serial Nor648,874 Divided and this application filed April 16, 1902. Serial No.

To all whom it may concern:

Be it known that I, CHARLES P. STEINMETZ, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in CompoundingAlternators, (Case No. 2,829, division of my prior application, SerialNo. 648,874, filed August 20, 1897,) of which the following isaspecification.

The object of my invention is to provide an efiicient method ofregulating alternatingcurrent generators of one or more phases both forchanges of load and changes of phase relation between current andelectromotive force in the main circuit. The field excitation of thegenerator should increase with increased load and with lagging currentand decrease with diminished load and with leading current.

I have designed the present invention to secure satisfactory regulationof the character described.

Various embodiments of the invention will be hereinafter particularlydescribed. The features of the invention,whether carried out in theseways or in other possible modified ways, are defined in the claims.

As a regulating means I have aimed to se-' cure an electromotive forceor electromotive forces which will rise and fall in value with changesof load and which will also rise when the main current lags and fall ifthe main current leads in a ratio corresponding with the changes of loador phase displacement. Having secured such an electromotive force orelectromotive forces, I am enabled to derive therefroma correspondingcurrent of changing value with which to properly regulate or control theregulation of the generator. As the load changes the current willcorrespondingly change, and from the current I can in a variety of wayssecure an electromotive force varying with theload, to this extentrealizing the object of the invention. Going astep farther, if anauxiliary electromotive force changing in value and phase withcorresponding changes of current is combined with an electromotive forcedeveloped in a coil on the generator (No model.)

and if the phase relation of the electromotive forces so combined issuch that the auxiliary electromotive force leads the generatorelectromotive force by a proper angle, such that when the current lagsthe two electromotive forces shift more nearlyin phase,and vice versawhen the current leads, then the resultant electromotive force due tothe combination will tend to increase in value with lagging currents andto decrease with leading currents, thereby securing an electromotiveforce changing both with the load and with the phase displacement whichrenders possible in practice the desired regulation. I have thereforeprovided means for deriving an auxiliary electromotive force of thecharacter described coupled with means for combining such anelectromotive force with a generator electromotive fo'rce having theproper relative phase relation and means for regulating or controllingthe regulation directly or indirectly of the generator by the resultantelectromotive force and current so obtained.

Describing now more specifically some of the ways of practicing theinvention, one method is to provide transformer devices, eithercompensators or ordinary two coil transformers, in the circuit of thegeneratorcurrent. The current will induce in the transformer device asecondary transformed electromotive force, changing in value and phasewith the current and practically in quadra' ture with the main generatorelectromotive force at non-inductive load,though this value varies withlag and lead of the current. This supplies the auxiliary electromotiveforce, which, as already explained, is combined with a generatorelectromotiveforce, thus furnishing resultant electromotive force andcurrent having the desired characteristics. A second method is to employreactive coils or other inductive impedances in place of thetransformendevices. Electromotive forces will thereby be inducedpractically ninety degrees behind the current, and in a three-phasemachine these electromotive forces will consequently be thirty degreesahead of the electromotive forces developed, respectively,in thegenerator-coils of the pre- ICO I refer to Figs. 10 and 11. 1 Let 00.represent.

ceding phase. Then by combining the elec= tro motive forces generated inthe impedances with the generator electromotive forces of the precedingphase resultant electromotive orcesand currents will also be securedrising and falling in value in the necessary and proper ratio.

The drawings annexed are diagrams showing different ways of carrying outthisinvention.

Figure 1 showsa three-phase machine with compensators in'the differentbranches of the machine. Fig. 2 shows a similar machine combined withinductive coils instead of compensators. Fig. 3 shows a modification.Figs. 4, 5, and 6 are diagrams introduced to help in explaining theworking of my invention as now understood. Fig. 7 is a diagram show ingan additional feature of the invention. Figs. 8 and 9 show ways ofapplying the invention to single-phase machines, and Figs. 10 and 11 arefurther explanatory diagrams.

I will first explain how the invention is applied to a single-phasemachine, since the connections are somewhat lessintricate. For thispurpose I refer to the figures on Sheet 3 of the drawings.

In Fig. 8, M is the'armature or generator winding of asingle-phasealternator. One terminal is connected toline through the collector-ring1, and the second terminal leads, as shown, to an intermediate point inthe winding of a compensator or single-coil trans-I former N. Oneterminal of the compensator leads to the line-circuit through the secondcollector-ring 2, and the-second terminal is brought back and tappedinto the generatorwinding, as at 3. The primary 6 of a twocoiltransformer O is included in circuit between the compensator and point3. The current developed in the secondary 7 of the transformer 0 may heused for regulating or controlling the regulation of the alternator in'a variety of ways. For this purpose I have shown a rotary converter of awellknown type, having a closed circuit-Winding connected at twodiametrically opposite points with the secondary of the transformer 0through collector-rings 4 and 5. The rectified current is taken fromcommutator 8 and passed through the exciting-winding P of thealternator. Such an arrangement will regulate in the manner described.

According to my present understanding of the invention I will nowexplain the electrical actions taking place when the described apparatusis in operation. For this purpose the electromotive force developed in aselected portion of the generator-winding M, the electromotive force ofthe winding M being represented by 0a, and 0c the generator-current, onthe assumption that the current is in phase with the electromotiveforce. The primary electromotive force developed in the compensator willbe practically in quadrature behind the current, as shown by dotted line00.. The-secondary transformed electromoti've force developed in thecompensator will be one hundred and eighty degrees from 00/, andtherefore practically ninety degrees ahead of the generatorelectromotive'force 00.. With the apparatus connected as described theelectromotive force in the primary circuit of the transformer 0 Willtherefore be the resultant 0a of electromotive forces 0a and oa If theload changes without change of phase, the component electromotive force0a will change in value correspondingly, and hence also the resultantelectromotive force. if the load becomes inductive and the current lags,as at 00 in Fig. 11, the auxiliary electromotive force 0a will shiftwith the current, approaching more nearly the generator electromotiveforce 0a.- The line oa representing the resultant electromotive force,is longer than the corresponding line in Fig. 10, showing that under thenew conditions the resultant electromotive force has an increased value;By co'nstructingasimilar diagram representing the main: current leadingit will be found that the line 0a shortens and the resultant electromotive force is reduced.

Fig. 9 has been introduced to show that an ordinary two-coil transformermaybe used instead of a compensator and that the generator electromotiveforce, with which the auxiliary electromotive force is combined, may bedeveloped in a separate winding. In this figure, M represents, asbefore, the main generator-winding,connected to line through (:01-lector-ring 1 and at the other terminal through the primary coil of atwo-coil transformervO and the second collector-ring 2.

A separate generator-winding M is provided, in which an electromotiveforce is developed, preferably, of the same phase as the electromotiveforce of the main winding. The secondary transformer O andthegenerator-winding M are connected in series, and the current developedin this circuit is used for regulating the alternator. For so doing Ihaveshown, as before, a rotary converter rectifying the alternatingcurrent and furnishing the exciting-current for the fieldmagnet windingP of the alternator.

In Fig. 1 the invention is shown as applied to a three-phase machine.Dis the field-magnet-exciting circuit wound in the ordinary way. Thearmature-coilsA' A A have, respectively cuit-mains 1 2 3 throughcollector-rings G (1 C The other terminals of the coils are connected tointermediate points in the windings of three correspondingcompensators'BB 'B One of the terminals of'each of these compensators is connected toa common joint at y,

one terminal connected to the cirso that, in effect, the armature-coilsare Y- The other terminal of "comconstructed to rectify the current inthe sec-v ondary-transformer circuits and deliver the rectified currentto the field-magnet winding of the machine.

The diagrams Figs. 4 and 5 are introduced to explain the actions takingplace in the machine of Fig. 1. These will be readily understood afterthe explanation already given of the actions in a single-phase machine.It is sufficient to note that the main generator three-phaseelectromotive forces are represented by lines 0a oa- 0a. In Fig. 4. thecurrents are assumed to he in phase and are therefore represented bylines 00 00 00 The secondary electromotive forces developed in thecompensators will be practically ninety degrees ahead of the maingenerator electromotive forces and currents and are represented by linesa b a b (L 11 The dotted lines ob 0b ob therefore represent theresultant clectromotive forces generated in the secondary circuits oftransformers T T T and used for supplying the exciting-current.

In Fig. 5 the current is shown lagging a few degrees behind thegenerator electromotive force, 0a 0a 0a representing the generatorelectromotive forces, and 00 0e 0c the currents, as before. Thesecondary electrometive forces in the compensators will shift with thecurrent, thereby forming a more acute angle with the generatorelectromotive forces when the current lags. The resultant electromotiveforces 01)" 0b 0b have,an increased value as compared with the diagramFig. 4, which of course means that the electromotive forces furnishingthe exciting-current have risen in value, thereby also raising thepotential of the machine and compounding for the lagging currents.

In Fig. 2 is shown a three-phase machine with inductive reactances forgenerating the auxiliary electromotive forces. D is the fieldmagnetwinding, and A A A the armaturecoils connected to line throughcollector-rings C 0 C as before. The arniaturecoils have their otherterminals connected at the common joint y through inductive coils I 1 1The transformers T T T have their primaries connected, respectively,across a portion of the winding of generator A A A The secondary oftransformer T is connected between the outer terminal of reactive coil 1and armature-coil A So, also, the secondary of transformer T isconnected between reactive coil 1 and armature-coil The secondary oftransformer T is connected between reactive coil I and armature-coil A.The free terminals of the transformer secondaries are connected throughleads m n19, collector-rings, and brushes to the alternating sides of athree phase rotary converter RC. Collector-rings 7' r r are provided forthe converter, of which t is the commutator from which the rectifiedcurrent is fed to the fieldmagnet winding D. The rotary converter isshown excited by a shunt-winding if, taken from the direct-current sideand including, if desired, the usual regulating-rheostat.

The construction described will work in accordance with my invention,though the actions are in certain respects difierent from thosepreviously described. These differences I will try to make clear byreferring to Fig. 6, in which 0a 0a 0a represent the generatorelectromotive forces, as before. suming first that the currents are inphase with their respective electromotive forces, 00 will represent oneof the currents. The auxiliary electromotive forces developed in thereactive coils will theoretically be ninety degrees behind thecorresponding currents, and therefore the auxiliary electromotive forcecorresponding to and generated by current 00 will be represented by 061061 is ninety degrees behind the generator electromotive force 068*, but(in the three-phase machine) thirty degrees ahead of the generatorelectromotive force of the preceding phase 0a. \Vith the connectionsshown in Fig. 2 the reactive electromotive force or] is combined with aneleetromotive force of the preceding phase 0a, giving, the resultant 06If new the current lags through a certain phaseangle represented by 00,the corresponding reactive electromotive force will shift backwardthrough a like angle approaching more nearly the generator electromotiveforce out, and the resultant of the combined electromotive forces 06will have an increased value. There are illustrated in the diagram theactions taking place in a single phase only of the machine in order torender the diagram less complicated. Those skilled in the art, however,will from this explanation readily understand the operation of thismodification as a whole.

In Fig. 3 is shown still another combination which maybe employed incarrying out the invention. Like parts are represented by the sameletters as in the otherdiagrams, and I will refer only to those pointsin which the construction is changed. The generatorcoils A A A are hereconnected to a common joint 1 through the primary coils of ordinarytwo-coil transformers. (Shown at T T T orator-coils and the transformerprimaries will induce the desired auxiliary electrometive forces in thetransformer secondaries. These auxiliary electro motive forces arecombined, as before, with generator electromotive forces; but thegenerator electromotive The currents flowing in thegenvary the length ofthat portion of thecomforces so combined are developed in separatewindings A A A on the generator. An examination of the diagram will showclearly how the transformer secondaries are interconnected at a commonjoint 3 The secondary of transformer T is connected in series with thegenerator-coil A, standing in the same phase as the main coil A, andthence to the lead n. The secondary of transformer T is likewiseconnected through generator-coil A", standing in the same phase withcoil A and to lead 10. The secondary of transformer T is connected tocoil A, of the same phaseas coil A and tothe lead m, so that theelectromotive forces developed in the secondaries of the transformersare combined with the generator electromotive forces developed in coilsA A A, giving suitable resultant electromotive forces and currents forcompounding the machine. In this modification the currents so developedare fed over the lines m n19 to the primary windings F I F of analternating-current three-phase induction-motor IM. The secondary of themotor is of high resistance, and its speed will vary within quite widelimits in proportion to the impressed voltage, rising with increasedvoltage, and vice versa. The induction-motor is shown geared to adirect-current-exciter machine E. This machine feeds current to theexciter-winding D of the alternator, and the exciting-current varies inthe proper ratio for regulating the alternator, increasing, of course,with an increased speed of the exciter, which results from an increasedvoltage in the primary circuit of the driving induction-motor. Thefield-circuitt of the exciter-machineis shown coupled across theterminals of the machine. In other Words, it is an ordinary shunt-woundexciter.

In Fig. 7 there are illustrated further features of the invention,showing how the compounding or regulating action may be varied in valueand character. For the sake of clearness there are illustrac'ted simplythese additional features applied to a simple branch of a three-phasemachine connected in other respects in the manner shown in Fig. 1. A isthe alternating winding, whose terminals are connected to line throughcollector-ring O and to the common joint y. The compensator B isincluded in this circuit, and transformer T is in circuit, as before,between one terminalof the compensator and a point in the maingenerator-winding. A switch S, connected to the inner terminalofgenerator-coilA, may be adjusted so as to pensator-coil included betweenthe generatorcoil and joint y. This is done by leading out taps 9 fromvarious points in the compensator-winding to contacts arranged in thepath of travel of switch S. This is a common expedient and will be wellunderstood. By adjusting the length of this portion of thecompensator-coils thevalue of the auxiliary electromotive forces for agiven current can be changed, because the ratio ofturns and of thetransformation taking place betweenthe two portions of thecompensator-winding is changed. In this way I adjust the amount ofcompounding. I show, furthermore, a non-inductive resistance R, shuntingthe compensator B, and a switch S for adjusting the value of theshunting resistance. In this way the nature of the compounding asregards phase displacement can also be adjusted. I

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. The method of regulating an alternatingcurrent generator, whichconsists in deriving from the'current of the generator an electromotiveforce whose phase relation varies with that of the generator-current,combining said electromotive force with a generator electromotive forceof such difierent phase relation that the combined electromotive forceswill produce a resultant electromotive force and current, which willtend to increase when the generator-current lags, and tend to decreasewhen the current leads, and regulating orcontrolling the regulation ofthe generator by the current so produced.

2. The method of regulating an alternatingcurrent generator, whichconsists in passing the current of the generator through an inductivedevice,,deriving thereby an electromotive force changing in strength andphase relation with the generator-current, combining said electromotiveforce with a generator electromotive force of suchdifferent phaserelation that the combined electromotive forces shift more nearly inphase when the current lags, and more out of phase when the currentleads, and regulating, or controlling the regulation of, the generatorby a current produced by such resultant electromotive forces and sharinglike changes in value, as set fort-h. V

In witness whereof I have hereunto set my hand this 14th day of April,1902.

CHARLES P. STEINMETZ.

